A light source device for a display device includes a planar light source and a monochrome liquid crystal panel. The monochrome liquid crystal panel includes a plurality of pixel electrodes. Pixel electrodes adjacent to each other in the plurality of pixel electrodes partially overlap each other within one pixel. The monochrome liquid crystal panel includes an exclusive region including a part of one of the plurality of pixel electrodes but not including the other pixel electrodes and an overlap region including parts of pixel electrodes adjacent to each other.